I'm planning to replace the boiler on a system that's over 20 years old. I put a proper in-line magnetic filter on it a couple of years ago after the combi DHW heat exchanger blocked and it's obviously had some magnetite deposits over the years. I was thinking to flush some (all?) of the rads manually first: good idea? What are the group views on the Sentinel / Fernox cleaners and sludge removers. Any ideas for a DIY power flush?
TIA
Is it gravity fed?
Do you feel like removing any radiators to take them outside for a flush through?
I didn't use any flushing agents - just lots of water. I drained each rad in turn, and took it outside and flushed it out with a hosepipe. While it was off, I flushed its flow and return pipes by opening each valve in turn and allowing water to flow into a container until it ran clear. I also devised a cunning way of flushing out the pipes running between airing cupboard and boiler, plus the indirect coil in the HW cylinder - but it was so cunning that I can't remember exactly what I did!
Fernox is better being strong. Follow the instructions well. Try Fermox first. Does the filter catch any magentite? Are there cold spots on the rads?
It must be bad if there are cold spots. I worry if my water looks like weak tea!
I would add Fernox or Sentinel X800 or equivalent cleaner and flush like mad.
Having used both, Fernox is better.
Did you write the Blackadder/Baldrick cunning plan scripts?
Look at the cost of anti-freeze for a car cooling system and then anti-freeze for a CH system. Both have pumps and lots of ferrous.
I have cold spots in my hall radiator, I am thinking of removing the rad and flushing it out, all my rads have TVR's fitted so it should make radiator removal easier.
But is a flush likely to cure the cold spots?
Stephen.
Could be really bad sludge. Does it take long for the flow and return pipes to get warm when first switching on?
I have not really noticed the heat difference in flow either way to be honest, but hall radiator seems to be very spasmodic, sometimes it is hot and sometimes it is cold in the middle, this morning though it was hot, I have no idea why.
All the radiators (five in all) are on the same level being a bungalow don't know if this makes any difference, but the hall radiator is turned full on at both valves.
Stephen.
Has the old system had inhibitor in it - and that renewed at the recommended times?
Are the others balanced? Assuming a reasonable original design, one rad not getting hot can be down to the other rads taking too much of the available flow.
No - my cunning plan (whatever it was!) actually worked!
In my view, it actually makes it slightly *harder* in that you need to make sure that the TRVs are fully turned off - which you can only do by removing the thermostatic head and fitting the 'decorating' cap supplied with the valve - if you can find it!
It could just be that the system needs balancing. You may not be getting the full flow through this rad - even when fully open - without throttling some of the others a bit. If this one is slow to warm up, a room stat elsewhere may be shutting the system down before it is fully hot.
If the radiators are only just big enough you might want to consider changing them to larger ones so you can run the new system efficiently with a 20=BAc difference across the flow and return.
You can take all the rads off and give them a good flush with a hosepipe outside and then once you have replaced all the radiators you can run something like Sentinel X400 for a few weeks and then flush it all out just to make sure all the crap has been removed. I cleaned our own system last year but I don't think it was as bad as yours; I used Sentinel X800 and ran each radiator individually for 20-30 minutes at maximum pump speed and maximum temperature, a lot of dirt did come out.
This seems an interesting way to go about things:
Not sure if the rads are balanced, the radiator adjustment can be altered by simply turning the knob, but none of the rads have a lockshield balancing valve, just a TVR and ordinary knob valve.
Stephen.
We don't have the original decorating caps that were supplied unfortunately.
Stephen.
We don't have a room thermostat with this system so I presume the rad could be throttled, I'll try altering the settings on the other rads when I fire up the heating later on today.
Stephen.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.